RU2394119C2 - Semipermeable materials for transport belts and press cloths - Google Patents

Abstract

FIELD: textile, paper. ^ SUBSTANCE: cloth is formed by arrangement of layers in a specified order. At least one layer includes woven, knit or wattled material, which has the first temperature of melting, lower than melt temperature of any other layer. When heating layers up to temperature that is at least equal to the first melt temperature but is below melt temperature of other layers, at least one layer melts without melting the other layers. ^ EFFECT: invention provides for cloth homogeneity and increased smoothness of its surface, which determines quality of paper produce made with application of its cloth. ^ 13 cl, 6 dwg

Description

Field of Invention

The present invention relates to the field of paper production, in particular, to the production of tissue for papermaking, machines for conveyor belts and press fabrics.

State of the art

In the paper manufacturing process, a cellulosic fibrous web is obtained by a method of applying a fibrous slurry (it is an aqueous dispersion of cellulosic fibers) onto a moving forming web. This operation is carried out in the forming part of the paper machine. A large amount of water is discharged from the slurry through the molding net, and a cellulosic fibrous web remains on the surface of the molding net.

Formed cellulose fiber web from the molding (mesh) part enters the press part, in which there are a number of press rolls. A cellulosic fibrous web supported by a press fabric (or, as is often the case, located between two press fabrics) passes through the press rolls, where it is subjected to compressive forces that squeeze water out of it, and cellulose fibers adhere to each other to form from a cellulose fibrous web of a sheet of paper. Water passes into the press fabric and ideally does not return to the sheet of paper.

At the final stage of production, a sheet of paper enters the drying section, which contains at least one row of rotatable drying drums, heated from the inside by steam. The formed sheet of paper passes along a wave-like trajectory, sequentially bending around each drum of the row. A sheet of paper is sent using a drying cloth, which presses it to the surface of the drums. The use of heated drums reduces the water content in a sheet of paper to the required level as a result of evaporation.

It should be noted that the forming mesh, press and dryer tissue of the paper machine are in the form of an endless loop and serve as conveyors. It should also be understood that the paper production process is continuous and proceeds at significant speeds. In the forming part, the fibrous suspension is continuously fed onto the forming grid, and the manufactured sheet of paper, after exiting the drying part, is continuously wound into rolls.

Press fabrics play an important role in the papermaking process. In particular, they perform the function of a substrate and transporting the produced paper product through the press rolls.

Press fabrics also participate in the final processing of a sheet of paper: they have a smooth surface and a uniformly elastic structure so that when passing through the press rolls the surface of the paper is smooth and without marks.

Perhaps the most important function is the absorption by the press fabric of a large amount of water, which is separated during the extraction from wet paper on the press rolls. In order to fulfill this function, the press fabric must have a space (which is usually called the void volume) for water, and the fabric must have adequate water permeability throughout its life. Finally, fabrics should not allow water to return to wet paper and re-wet it at the exit of the press rolls.

Currently, a wide variety of press fabrics is produced in accordance with the requirements of paper machines for which they are designed to be installed in order to ensure the required quality of the produced paper. Usually they consist of a textile fabric base on which a thin non-woven fiber is fixed by needle-piercing. The warp can be woven from monofilament, twisted monofilament, multifilament yarn, twisted multifilament yarn; the fabric may be single layer, multi-layer or laminated. In this case, yarns obtained by extrusion from any synthetic resin selected from a variety of resins, for example, such as polyamide and polyester resins, known to those skilled in the art of equipping papermaking machines, are commonly used.

Textile backings can have a different shape. For example, they can be in the form of an endless loop or initially smoothly stitched with subsequent stitching into an endless shape using a textile thread. Alternatively, they can be made using technology known as modified endless textile, in which the edges along the width of the warp have suture loops with threads oriented in the machine direction (MH). In this process, MH threads are woven continuously back and forth between the edges of the fabric, turning backward at each end and forming a suture loop. The base obtained in this way is infinitely shaped during installation on a paper machine, and for this reason it is called fabric stapled in a paper machine. To give such an fabric an infinite shape, the two edges are brought together, the suture loops are connected to each other by a comb method, and the stapling pin or pin is threaded through the resulting structure formed by the comb stitch loops.

In addition, the textile backings can be laminated by placing one backing inside an endless loop formed from another backing, with both backing being stitched with staple fiber to connect them. One or both of the textile backings can be fabrics sewn in a paper machine.

Thus, the textile backbone is either an endless loop or has a shape that allows them to be sewn in the form of an endless loop; further, they are characterized by a predetermined length, which is measured in the fractional direction of the fabric along the circumference, and a predetermined width, which is measured in the transverse direction of the fabric. Due to the fact that the configurations of papermaking machines are very diverse, manufacturers of fabrics for papermaking machines should accordingly ensure the release of press and other fabrics, the sizes of which correspond to the sizes of specific parts of papermaking machines of consumers. There is no need to say that such requirements make it very difficult to organize mass production, since each specific press fabric must be made to order.

In accordance with the above-described need for press fabrics of different lengths and widths, in recent years, production has been carried out using a spiral technology, which is described in US Pat. No. 5,360,656 (Rexfelt et al.), The contents of which are incorporated herein by reference.

US Pat. No. 5,360,656 describes an extruded fabric comprising a backing having one or more layers of sewn-in staple fibrous material. The base includes at least one layer consisting of a wound strip of woven material having a width less than the width of the base. The base is infinite in the longitudinal direction (or machine direction). The turns directed along the length of the winding strip are at an angle to the machine direction of the press cloth. A strip of woven material may be smoothly spun (produced on a loom). The specified machine is narrower than those that are usually used in the manufacture of equipment for paper machines.

The base contains wound and connected spiral coils from relatively narrow strips of fabric material. The fabric strip is woven from longitudinal (main) and transverse (filling) threads. Adjacent coils of a wound fabric strip may abut each other, and a spiral-shaped continuous seam can be made by stitching, fusion (for example, ultrasound) or gluing. Alternatively, adjacent longitudinal portions of the edges connecting the coils of the spiral can be superimposed on top of each other, provided that the edges are thinner to prevent an increase in thickness in the overlapping area. Moreover, the distance between the longitudinal threads can be increased along the edges of the strip, so that in the case when the adjacent turns of the spiral overlap, the distance between the longitudinal turns in the overlapping area remains unchanged.

In addition, it can be noted that the conveyor belts are used to transfer a sheet of paper between separate parts or between elements of parts (such as separate presses in the press part) of a paper machine. Transport belts can be designed to perform the function of transferring a sheet of paper on a separate section of the paper machine, as well as for dewatering paper.

As mentioned above, the main function of all tissue paper machines is the dehydration of a sheet of paper. In addition, criteria such as surface smoothness and uniformity are important factors to consider when manufacturing fabrics for paper machines. Topography of the surface of fabrics determines the quality of paper products. Efforts have been made to create a smoother surface in contact with a sheet of paper. However, the smoothness of the surface or the press uniformity of the fabric for the paper machine is limited by the topography, which is due to the pattern of weaving of the fabric threads and the physical properties of the fabric under the sewn-in fibrous layer. In a fabric (or knitted) material, smoothness is initially limited by the bending of the threads formed at the intersection point. Therefore, there is a need for fabrics with increased smoothness and uniformity.

It is known from the prior art to produce fabrics for paper machines by fusing non-woven materials such as staple fiber or spun fiber. The location and orientation of the staple material fibers is random and cannot be specified or reproduced in different tissues. This also applies to the case when, to obtain a smooth surface, a film coating of a film of fused material is used; film swelling occurs (usually in the direction of the heat source). The swelling process is heterogeneous; these films or “coatings” used in previous technologies, only slightly reduce the heterogeneity of the pressure distribution applied to the base fabrics, which serve as the supporting structure of the press fabrics.

For example, US Pat. No. 4,565,735 describes a paper machine cloth with an anti-shrink cushion layer sewn to one or both sides of a woven backing. The cushioning layer (s) are obtained from a mixture of at least two types of fibers. The first type is present only in small quantities and has a melting point lower than the melting temperature of the rest of the cushioning layer (s) and the base. Cloth is heated to a temperature higher than the indicated lower melting point, and the first fibers melt, binding the remaining fibers to each other and to the base. Despite the fact that this allows you to achieve some improvements in the field of local binding of the fibers, however, almost no improvements were noted in relation to improving the smoothness of the surface or masking the structure of the base.

US Pat. No. 4,380,915 describes a cloth for a dewatering press of a paper machine. Cloth has several layers of non-woven fiber, alternating with layers of a polymer network. The mesh layers have a lower melting point than the fiber layers. The fiber layers can be fixed by needle-punched, stitched, heated, or some combination of these methods. Each mesh layer is preferably made in the form of a nonwoven mesh material. During manufacture, the felt may be heated to a temperature higher than the softening temperature of the polymer net. However, the cloth is not heated to the melting temperature of the polymer network. As a result, it is not possible to obtain smoothness and / or uniformity of pressure.

DE 29706427 U1 describes flexible tapes used in paper machines. The tape has at least one side that contains an impermeable layer and exhibits elastic properties under compression. A characteristic feature is that the impermeable layer is obtained by melting fibers of a fibrous structure on one side of the tape. The fibrous layer or nonwoven layer contains a predetermined amount of thermoplastic deformable threads or a thread of hot-melt adhesive. As mentioned above, the arrangement of the fibers in the nonwoven layer is not uniform and cannot be reproduced from cloth to cloth. Also described invention is a woven coating obtained from the so-called two-component yarns. These threads are coated with hot melt polymers. Under the influence of heat, the above coating melts, and the thread remains in its previous state. The resulting molten material provides an adhesive bond. Thermoplastic deformable threads do not allow to obtain higher characteristics of smoothness, because only the coating melts, and the core remains untouched.

US Patent No. 5,298,124 (of which Albany International Corporation is the copyright holder) describes a transport tape, the contents of which are incorporated herein by reference. The specified transport tape is characterized by a pressure-dependent surface topography and a restored level of roughness. Thus, under the influence of pressure on the press roll, the level of roughness is reduced, which makes it possible to form a thin water film between the transport tape and the sheet of paper, which connects the sheet of paper with the transfer tape at the exit of the press roll. When the initial level of roughness is restored some time after exiting the press roll, the sheet of paper can be removed from the conveyor belt, possibly using a minimum vacuum or pumping air from a permeable fabric (such as a drying cloth).

US Pat. No. 5,298,124 describes a sheet transfer belt that may include a reinforcing base that has a side in contact with the paper and a back side. The specified tape on the paper side may have a polymer coating, which contains a balanced distribution having segments of at least one polymer. The balanced distribution has the form of a polymer matrix, which may contain both hydrophobic and hydrophilic polymer segments. The polymer coating may also contain particulate filler. The reinforcing base serves to reduce the longitudinal and transverse deformations of the transport tape; it can be made of fabric material and, in addition, can be endless or stitched into an endless shape during installation in a paper machine. The reinforcing base may have one or more staple fiber layers secured by needle-piercing to the reverse side. A layer or layers of staple fiber, also called needle-punched fabric, is attached to the back of the reinforcing base in order to control the degree of impregnation of the reinforcing base with a polymer coating on the paper side. During operation of the conveyor belt in a paper machine, the needle-punched web protects the threads of the reinforcing base from abrasion.

SUMMARY OF THE INVENTION

The present invention is directed to the creation of a conveyor belt or press fabric, which have at least one woven, knitted or woven layer with a melting point below the melting point of the remaining layers. The fabric is exposed to temperature, as a result of which the molten layer melts, and the rest of the structure remains without technical changes. The advantage of this layer is that the location and location of the molten material is known in advance.

Accordingly, the present invention is a tissue for paper machines and a method of forming tissue paper machines, comprising the steps of:

placing several layers in a predetermined order, and at least one layer contains a material that is woven, knitted or braided and has a first melting point, and all other layers have a higher melting point than said first melting point;

heating the layers to a temperature at least equal to the first melting temperature, but lower than the melting temperature of the remaining layers; thus, said at least one layer melts without melting the remaining layers.

BRIEF DESCRIPTION OF THE FIGURES

The following detailed description provides examples of implementation, not limiting the scope of the present invention and accompanied for better understanding by the accompanying figures, in which the same reference numbers denote the same parts.

Figure 1 presents a cross-section of fabric for a paper machine, consisting of several layers, including in accordance with the present invention one meltable woven, knitted or braided layer;

FIG. 2 is a cross-sectional view of a first alternative embodiment of fabric for a paper machine consisting of several layers, comprising, in accordance with the present invention, two fusible woven, knitted or woven layers;

FIG. 3 is a cross-sectional view of a second alternative embodiment of fabric for a paper machine consisting of several layers, including, in accordance with the present invention, two melting woven, knitted or woven layers;

Fig. 4 is a cross-sectional view of a third alternative embodiment of fabric for a paper machine consisting of several layers, comprising, in accordance with the present invention, two melting woven, knitted or woven layers;

5 is a cross-sectional view of a fourth alternative embodiment of fabric for a paper machine consisting of several layers comprising, in accordance with the present invention, two fusible woven, knitted or woven layers;

Fig. 6 is a cross-sectional view of a fifth alternative embodiment of fabric for a paper machine consisting of several layers comprising, in accordance with the present invention, a meltable woven, knitted or braided layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention can be applied to fabrics used in press and other parts of a paper machine, as well as for fabrics used in other industries, including (but not limited to) fabrics for conveyor belts, fabrics for final pressing, fabrics for web removal, fabrics for calendaring.

The proposed method for producing fabric for a paper machine includes producing an endless continuous fabric that is initially endless or contains a seam that allows you to set the fabric in the same form as a traditional stitched press fabric known in the industry. The specified fabric may contain a carrier layer, that is, the base. The carrier layer can be made of any structure used as a basis for equipping a paper machine: woven or non-woven, woven or knitted material, an extruded sheet of polymer resin material, an extruded mesh material or fabric with spiral turns. The carrier layer can also be assembled from a strip of one of these materials spirally wound into coils, each coil being connected to the adjacent one by means of a continuous seam.

The carrier layer may also be a laminated structure comprising two or more fabrics, each of which may be made of one of the structures indicated above. In the event that the carrier layer is laminated, one of the constituents of the base can be sewn together when installed in a machine, and thus, the tape can be sewn into an endless shape when installed in a paper machine.

A staple fibrous material may be embedded in the carrier layer. One or more layers of staple fibrous web can be fixed by needle punching on the carrier layer, while the web can fully or partially protrude from it. A web of staple fibrous material may also form a layer covering the surface of the carrier layer.

Staple fibrous material, sewn needle-punched into the carrier layer, can be made of any synthetic polymer resin (for example, polyamide) used by specialists in this field.

The carrier layer may be woven or assembled from threads, including any threads that are used in the manufacture of equipment for paper machines and in fabrics for industrial processes. Namely, the carrier layer may comprise monofilament, twisted monofilament, a multifilament yarn, twisted multifilament yarn or filaments formed from staple fiber obtained from any synthetic polymer resin used by those skilled in the art.

At least one layer of tissue for a paper machine comprises a melting layer. The specified layer may be woven, knitted or woven and have a melting point lower than the melting temperature of each of the remaining layers of fabric of the paper machine. The melting layer can be woven, braided or otherwise assembled from yarns, including any yarn that is used in the manufacture of fabric for a paper machine. In other words, the melting layer contains a material that has a lower melting point than any of the other layers of the structure (the melting layer is called “material with a low melting point”). For example, the melting layer may be made of threads obtained from the following materials: polyethylene, polypropylene, low melting point polyamides, polyurethanes, polyolefins or other materials used by specialists in this field. A consumable coating can be 100% composed of a material with a low melting point or a combination of a material with a low melting point and other materials having a higher melting point. For example, a consumable material 100% composed of a material with a low melting point can be used in a conveyor belt for transporting sheets. However, there are applications in which complete melting is not required, for example, if it is necessary to obtain a given porosity (permeability). Accordingly, in this case, the content of the material with a low melting point may be less than 100%. In other words, the melt layer may contain non-consumable materials. Moreover, the woven, knitted or braided material may be in the form of a single layer of woven material or a structure of several layers suitable for this purpose.

The layers can be arranged in a predetermined order with the condition that at least one layer contains material having a melting point significantly lower than that of the remaining layers. The specified meltable fibrous layer (s) may be any layer of the structure, for example, upper or lower with respect to the carrier layer, or may occupy any position in the structure of the needle-punched layer (including the position immediately below the upper layer of the lining fibers or between any layers). In addition, the melt layer (s) can also be located directly on any surface of the cloth.

The layers can be joined by cross-linking, lamination or other methods used for this purpose by specialists in this field.

The resulting structure is then subjected to temperature, which allows the molten layer to melt, while the remaining layers as a result of the process remain unchanged, that is, intact and unmelted. In other words, the layers are heated to a temperature at least equal to the first melting temperature, but lower than the melting temperature of any of the remaining layers. Thus, at least one of the molten layer is melted without melting the remaining layers of the structure, and the result is a permeable fabric with higher characteristics of smoothness and / or uniformity of pressure. Since the melt layer is woven, knitted or woven, the melt material is more evenly and predictably distributed in the resulting structure compared to nonwoven fibrous materials. In addition, unlike non-woven fiber melt materials, a woven, knitted or braided fiber layer allows a precisely known location of the melt material (s) to be achieved. Also, if necessary, it is possible to obtain an impenetrable structure. In addition, unlike fabrics known from the prior art, the molten material to some extent retains integrity even after melting.

Accordingly, the fabric proposed in the present invention may be permeable or impermeable. In addition, the fabric proposed in the present invention may have improved uniformity of pressure due to the presence of a woven, knitted or woven fused layer, "masking" the unevenness inherent in the carrier layer.

We turn to a more detailed consideration of the drawings. Figure 1 presents a side view of a cross section of fabric (110) for a paper machine. An advantage of the present invention is that it can be applied to a wide variety of fabrics for paper machines (including, but not limited to) conveyor belts, press fabrics for finishing, fabric removal fabrics, calendering fabrics) and has a flexible range of properties for many different applications in the paper industry.

In the example shown in FIG. 1, the paper machine fabric (110) consists of a carrier layer (120), a sewn fibrous cushion layer (130) and (150), and a meltable woven, braided or knitted layer (140). In this example, the molten layer (140) includes a material that is woven, knitted or woven and has a first melting point. In addition, the carrier layer (120), the sewn fibrous cushioning layers (130) and (150) are composed of materials having a melting point higher than the melting temperature of the molten layer (140). After the layers are arranged in a specific order, they can be connected by any of the methods (for example, stitching or lamination) used by specialists in this field. After the layers are connected, the structure is heated to the first melting point.

2 is a side cross-sectional view of a tissue (210) for a paper machine. The fabric (210) consists of a carrier layer (220), sewn fibrous cushioning layers (230) and (250) and molten woven, woven or knitted layers (240) and (260). The molten layers (240) and (260) include materials that are woven, knitted or braided and have a melting point lower than each of the carrier layers (220) and the sewn fibrous cushion layers (230) and (250). As indicated above, the coatings are arranged in a specific order, connected and then heated.

3 is a side cross-sectional view of a fabric (310) for a paper machine. The fabric (310) consists of a carrier layer (320), a sewn fibrous cushion layer (330), a filament layer (370) (which may be woven, non-woven or wound), a non-woven layer (350), and a meltable woven, woven, or knitted layer ( 340) and (360). In the present example, the filament layer (370) may also be wound and may or may not contain nonwoven materials. The fusible layers (340) and (360) include a material that is woven, knitted or woven and has a melting point lower than the melting temperature of each carrier layer (320), the sewn fibrous cushion layer (330), the filament layer (370) and non-woven layer (350). As indicated above, the layers are arranged in a specific order, laminated and then heated.

4 is a side cross-sectional view of a fabric (410) for a paper machine. The fabric (410) consists of a carrier layer (420), layers (430), (450) and (470) (which may be nonwoven or in the form of a fibrous cushion layer) and melt layers (440) and (460). In the present example, the carrier layer (420) is a warp knitted fabric. The melting layers (440) and (460) include a material that is woven, knitted or braided and has a melting point lower than the melting temperature of each carrier layer (420) and layers (430), (450), (470). As indicated above, the layers are arranged in a specific order, connected, and then heated.

5 is a side cross-sectional view of a fabric (510) for a paper machine. The fabric (510) consists of a carrier layer (520), layers (530) and (550) (which may be non-woven or in the form of a fibrous cushion layer) and melt layers (540) and (560). In the present example, the carrier layer (520) may be in the form of a wound strip of material. The melt layers (540) and (560) include a material that is woven or braided and has a melting point lower than the carrier layer (520) and layers (530) and (550). As indicated above, the layers are arranged in a specific order, connected, and then heated.

6 is a side cross-sectional view of a fabric (610) for a paper machine. The fabric (610) consists of a carrier layer (620), a layer (630) (which may be non-woven or in the form of a fibrous cushion layer) and a melt layer (640). The molten layer (640) includes a material that is woven, knitted or braided and has a melting point lower than the melting temperature of the carrier layer (620) and the layer (630). As indicated above, the layers are arranged in a specific order, combined and then heated.

Modifications of the present invention (taking into account the present description), but beyond the scope of the attached claims, are obvious to those skilled in the art.

Claims (13)

1. A method of producing tissue for a paper machine, comprising the steps of:
placing several layers in a predetermined order, at least one layer comprising a material that is woven, knitted or braided and has a first melting point, and the remaining layers have melting points higher than said first melting temperature;
heating the specified number of layers to a temperature at least equal to the specified first melting temperature, but lower than the melting temperature of each of the remaining layers; however, at least one of the layers is melted without melting the remaining layers. 2. The method according to claim 1, characterized in that the first layer includes a carrier layer, wherein said carrier layer is a woven, non-woven, knitted, woven, spirally connected or wound strip of material. 3. The method according to claim 2, characterized in that the second layer includes a fiber layer, while the specified layer of fiber is sewn to the specified carrier layer and it protrudes at least partially. 4. The method according to claim 1, characterized in that at least one layer is an endless woven, smooth-woven or wound strip of material. 5. A tissue for a paper machine, comprising several layers arranged in a predetermined order, wherein at least one layer contains a material that is woven, knitted or woven and has a first melting point, each of the remaining layers having a melting point of more than higher than the first melting point; and at least one of these layers melts when heated to a temperature at least equal to the first melting temperature, but lower than the melting temperature of each of the other layers, so at least one of these layers is melted without melting the remaining layers. 6. The fabric according to claim 5, characterized in that the first layer is a carrier layer. 7. The fabric according to claim 6, characterized in that the second layer is a fiber layer. 8. The fabric according to claim 7, characterized in that said fiber layer is sewn to the carrier layer and protrudes beyond it, at least partially. 9. The fabric according to claim 7, characterized in that the carrier layer is a woven, non-woven, knitted, woven, spirally connected or wound strip of material. 10. A fabric according to any one of claims 5 to 9, characterized in that said material is selected from the group consisting of polyethylenes, polypropylenes, polyamides, polyurethanes and polyolefins. 11. The fabric according to any one of claims 5 to 9, characterized in that it is a press fabric. 12. The fabric according to any one of paragraphs.5-9, characterized in that it is a transport tape. 13. The fabric according to any one of claims 5 to 9, characterized in that at least one layer is an endless woven, smooth-spun or wound strip of material.

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